About 1:40 p.m., officers were called to the 3100 block of Allston Way, to Caldwell Park in the Civic Center District.

Witnesses told police they saw the toddler yelling for his mom, but Perez pushed him away and then exited the park, according to officers.

"It's terrible," said Kenneth Valentine, who was at Caldwell as the situation unfolded. "I don't like to see little kids get hurt."

Valentine said a group of people looked around the park, checked the bathrooms, and when they still couldn't find the mother, they called 911 -- prompting the police response.

Officers arrived and took the child into protective custody. About 15 minutes later, found Perez walking out of the Smart Foods grocery store, behind the park.

"When they went to make contact with the mother, she had this appearance like, she was shocked we were there," said Joe Silva, of the Stockton Police Department. "We're still trying to learn why she abandoned her child and what led up to this."

The boy will remain with Child Protective Services as the investigation continues.

Perez is being held at the San Joaquin County Jail.

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